Department of Materials Science and Engineering and A. J. Drexel Nanomaterials Institute, Drexel University, 3141 Chestnut Street, Philadelphia, PA, 19104, USA.
Centre for Clean Energy Technology, School of Mathematical and Physical Sciences, University of Technology Sydney, Broadway, Sydney, NSW, 2007, Australia.
Adv Mater. 2017 Oct;29(37). doi: 10.1002/adma.201702410. Epub 2017 Jul 25.
2D transition metal carbides and nitrides, named MXenes, are attracting increasing attentions and showing competitive performance in energy storage devices including electrochemical capacitors, lithium- and sodium-ion batteries, and lithium-sulfur batteries. However, similar to other 2D materials, MXene nanosheets are inclined to stack together, limiting the device performance. In order to fully utilize MXenes' electrochemical energy storage capability, here, processing of 2D MXene flakes into hollow spheres and 3D architectures via a template method is reported. The MXene hollow spheres are stable and can be easily dispersed in solvents such as water and ethanol, demonstrating their potential applications in environmental and biomedical fields as well. The 3D macroporous MXene films are free-standing, flexible, and highly conductive due to good contacts between spheres and metallic conductivity of MXenes. When used as anodes for sodium-ion storage, these 3D MXene films exhibit much improved performances compared to multilayer MXenes and MXene/carbon nanotube hybrid architectures in terms of capacity, rate capability, and cycling stability. This work demonstrates the importance of MXene electrode architecture on the electrochemical performance and can guide future work on designing high-performance MXene-based materials for energy storage, catalysis, environmental, and biomedical applications.
二维过渡金属碳化物和氮化物，称为 MXenes，在包括电化学电容器、锂离子电池和锂硫电池在内的储能设备中引起了越来越多的关注，并表现出了竞争性能。然而，与其他二维材料类似，MXene 纳米片倾向于堆叠在一起，限制了器件性能。为了充分利用 MXenes 的电化学储能能力，本文通过模板法将二维 MXene 薄片加工成空心球和 3D 结构。MXene 空心球稳定且易于分散在水和乙醇等溶剂中，展示了其在环境和生物医学领域的潜在应用。由于球与 MXenes 的金属导电性之间的良好接触，3D 大孔 MXene 薄膜具有独立、灵活和高导电性。将其用作钠离子存储的阳极时，与多层 MXenes 和 MXene/碳纳米管杂化结构相比，这些 3D MXene 薄膜在容量、倍率性能和循环稳定性方面表现出了显著的改善。这项工作证明了 MXene 电极结构对电化学性能的重要性，并为设计用于储能、催化、环境和生物医学应用的高性能 MXene 基材料的未来工作提供了指导。
